Spatiotemporal regulation of liquid-like condensates in epigenetic inheritance

Non-membrane bound organelles such as nucleoli, processing bodies, cajal bodies, and germ granules form via spontaneous self-assembly of specific proteins and RNAs. How these biomolecular condensates form and interact are poorly understood. Here we identify two proteins (ZNFX-1 and WAGO-4) that localize to C. elegans germ granules (P granules) in early germline blastomeres. Later in germline development, ZNFX-1/WAGO-4 separate from P granules to define an independent liquid-like condensate that we term the Z granule. In adult germ cells, Z granules assemble into ordered tri-droplet assemblages with P granules and Mutator foci that we term the PZM granule. Finally, we show that one biological function of ZNFX-1 and WAGO-4 is to interact with RNAs in the C. elegans germline to promote transgenerational epigenetic inheritance (TEI). We speculate that the temporal and spatial ordering of liquid droplet organelles may help cells organize and coordinate the complex RNA processing pathways underlying gene regulatory systems, such as RNA-directed TEI. Small RNA sequencing of WT, znfx-1 and wago-4 animals in P0 and F1 generations after feeding oma-1 RNAi. Total RNA seq was done in order to capture small RNA population around the gene targeted with or without dsRNA (oma-1). We use two mutants (znfx-1 and wago-4) to ask whether the dsRNA directed small RNAs are dependent on these two genes.